(1) Field of the Invention
The present invention relates to a file management apparatus. More particularly, the present invention relates to a file management apparatus and a file management method which are suitable for the case where each file is composed of logical units (segments).
(2) Description of Related Art
General-purpose operating systems have a file system (file management apparatus) for managing files, as one of the functions thereof. The file management apparatus uses names of files (file names) stored in a storage apparatus. The file names and storage positions of files are registered with a directory (catalog). When a user requests to read or write data from/into a file specifying a file name, the file management apparatus refers to the directory to detect a storage position of a file having the file name, and reads or writes the file from/into the storage apparatus. Suppose, for example, a user in an FTP system composed of FTP clients and an FTP server sends a request specifying a file name from an FTP client, then the FTP client sends a request command including the file name to the FTP server. The file management apparatus in the FTP server refers to the directory to detect a storage position of a file having the file name reads the file from the storage apparatus, and sends the read file to the FTP client.
In the above-described system, the user need not be conscious of the storage position of the file, but just specify the file name to access the file.
Meanwhile, some files include logical units (segments). For example, a file may include different pieces of video data which are recorded at different times. In this case, some portions in the file are consecutive in the time domain and other portions are not. That is to say, a logical unit is formed based on the time-domain continuity of the portions in a file. More specifically, a sequence of portions that are consecutive in the time domain form a segment, and a gap between non-consecutive portions is regarded as a gap between segments.
A user may want to transfer or reproduce one specific segment among a plurality of segments contained in a file, as well as the whole file. To achieve this, the user has to find gaps between segments one by one as he/she produces the file after reading it from a storage apparatus, write down the addresses of the gaps, and input a written-down address to the file management apparatus to access a desired segment. The file management apparatus accesses the segment using the address input from the user. However, this operation is very complicated and it becomes a heavy burden to the user.